Proper humidification is essential for cigars or other items that have storage recommendations requiring specific relative humidity levels. Passive methods of humidification include the natural evaporation of ambient moisture. In passive humidification methods, moisture naturally evaporates from a solid state medium, typically a porous membrane, such as a sponge or foam-type material, a fibrous grid or matrix, a hygroscopic salt, or a polymer designed to expand and contain moisture, as exhibited in U.S. Pat. Nos. 5,975,288; 7,892,327; 5,936,178; and 8,087,645 respectively. The rate of evaporation is not able to be controlled, thus a precise and consistent relative humidity cannot be achieved. Furthermore, the relatively slow rate of natural evaporation is not sufficient to rapidly establish a selected relative humidity in an enclosure, specifically a cigar humidor or other enclosure that is repeatedly opened and needs to be repeatedly humidified.
Active methods of humidification have been designed to accelerate natural evaporation. Existing practices of active humidification employ the use of a humidity sensor and a fan working in conjunction to accelerate the process of passive humidification, as exhibited in U.S. Pat. Nos. 5,400,612; and 5,651,262. The humidity sensor activates the fan at a set point, generating a release of humidified air with a non-specific relative humidity. The humidified air typically has a relative humidity level that is much higher than the set point at which the sensor is triggered. The humidified air is emitted until the set point of relative humidity is reached, as detected by the sensor, at which point the fan is deactivated. As humidity dissipates and the sensor detects a relative humidity level below the set point, the fan turns on and the emission of humidified air is reactivated. The result is an environment with a cyclic fluctuation of relative humidity and an atmosphere in which the relative humidity of a location is dependent on proximity to the fan or sensor of the humidification device.
A method that specifically controls the relative humidity of emitted air can actively establish and sustain a selected relative humidity inside a storage container. Humidity sensitive materials benefit from storage conditions that are not subject to the humidity variations associated with uncontrolled moisture release and proximity to the humidification source or sensor.